1. Field of the Invention
The present invention relates to a battery-driven working machine for carrying out various works by electric power from a battery mounted thereon.
2. Description of the Related Art
A working machine of a battery driving system for carrying civil engineering works by electric power from a battery mounted thereon is disclosed in Japanese Utility Model Laid-Open Hei-4-53846 Publication. In this working machine, an electric motor is driven by electric power from a battery, a hydraulic pump is operated by the drive of the electric motor, a hydraulic motor is driven by working oil discharged from the hydraulic pump, and a working member such as a shovel is operated by the drive of the hydraulic motor.
The working machine of the battery driving type produces less noise than a working machine of an internal combustion engine type using an internal combustion engine as a driving source such as a gasoline engine, a Diesel engine or the like. Further, the working machine of the battery driving type does not discharge exhaust gas. Therefore, this working machine is suitable for works at a city area where buildings are thickly settled.
However, the condensing ability of the mounted battery as a power source of an electric motor is not larger than a fuel storing ability of the working machine of the internal combustion engine type, and therefore the former type machine cannot be used for a long period of time as compared with the latter type machine. Accordingly, the condensing amount of the battery tends to use up dung the operation in the working site. In this case, since the working member becomes disabled, the working machine body cannot be moved and sometimes cannot be moved in the working site.